CN1592450A - Front-end modules for mobile communication systems - Google Patents

Abstract

A front-end module for a mobile communication system includes a frequency duplexer, a plurality of transmit/receive switches, a low pass filter, a band pass filter, an impedance matching circuit, and a balun. The frequency duplexer is connected to an antenna, and the transmit-receive switch is connected to the frequency duplexer to switch the antenna to a transmitting end or a receiving end of the mobile communication system. The band-pass filter is connected between the receiving and transmitting switch and the receiving end, and the low-pass filter is connected between the receiving and transmitting switch and the transmitting end. The impedance matching circuit is connected between the two band-pass filters, and an unbalanced-to-balanced converter is connected between the impedance matching circuit and the receiving end.

Description

Front-end modules for mobile communication systems

technical field

The present invention relates to a front-end module for a mobile communication system, in particular to a front-end module suitable for a multi-band mobile communication system.

current technology

At present, most mobile phones on the market are dual-band and triple-band. The dual-band is to switch between 900 MHz and 1800 MHz, and the triple-band is to switch between 900 MHz, 1800 MHz and 1900 MHz. Due to limited frequency resources, some countries have recently opened up the 850 MHz frequency band to the GSM/GPRS system. In the United States, 850 MHz is mainly used to enhance the network capabilities of large cities with high density areas; and in South America, many countries only use 850 MHz MHz band. The four-band mobile communication system adds an 850 MHz frequency band, and supports functions such as multimedia applications, high-speed connection, and fast download of voice and pictures, which can realize unimpeded global roaming of mobile phones.

Therefore, it is necessary to design a mobile communication system front-end module that can be matched to quad-band to meet future requirements. At the same time, the front-end module of the mobile communication system matched to quad-band will contain a large number of components such as capacitors, inductors, resistors, filters, etc. Therefore, there are often disadvantages such as low reliability, high cost, and large size in assembly. To solve these problems, these components must be modularized and miniaturized.

Contents of the invention

Therefore, the purpose of the present invention is to provide a mobile communication system front-end module design that can be matched to quad-band, and the front-end module is made by a low temperature co-fired ceramic (Low Temperature Cofired Ceramic; LTCC) method to make it miniaturized.

According to the present invention, a front-end module for a mobile communication system includes a frequency duplexer, a plurality of transceiver switches, a low-pass filter, a band-pass filter, an impedance matching circuit and an unbalanced-to-balanced converter. The frequency duplexer is connected to an antenna, and the transceiver switching switch is connected to the frequency duplexer to switch the antenna to the transmitting end or the receiving end of the mobile communication system. The band-pass filter is connected between the transceiving switch and the receiving end, and the low-pass filter is connected between the transceiving switch and the transmitting end. The impedance matching circuit is connected between the two bandpass filters, and an unbalanced to balanced converter is connected between the impedance matching circuit and the receiving end. Designed by the front-end module architecture, it can be fully matched to the quad-band mobile communication system.

Furthermore, the front-end module of the present invention is formed in a patterned manner, including a frequency duplexer, a low-pass filter, a band-pass filter, an impedance matching circuit, an unbalanced to a balanced converter, and a part of the transceiver switch circuit formed on each layer Low temperature co-fired ceramic substrate inside. Since these components are composed of passive components such as resistors, capacitors, and inductors, passive components such as resistors, capacitors, and inductors are formed inside each layer of low-temperature co-fired ceramic substrates, and the front-end module of the present invention Integrate into various layers of low temperature co-fired ceramic substrates. Since the ceramic substrate has a high dielectric value, the present invention embeds components in a multilayer ceramic substrate in a patterned manner and integrates them, which can effectively integrate semiconductor components and passive components and greatly reduce the volume of the components. Therefore, The front-end module of the invention can simultaneously meet the requirements of module miniaturization and low cost.

Brief description of the drawings

FIG. 1 is a block diagram showing a front-end module of a quad-band mobile communication system according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a multilayer low temperature co-fired ceramic substrate used in the present invention, and a printed resistor is also displayed on the surface of the substrate.

FIG. 3A is a schematic diagram showing an inductor configuration when manufacturing the front-end module of the mobile communication system of the present invention.

FIG. 3B is a schematic diagram showing a configuration of capacitors when manufacturing the front-end module of the mobile communication system of the present invention.

Description of component symbols

10 front-end modules

12 frequency duplexer

14, 16 Transceiver switch

18, 28 low pass filter

20, 22, 24, 26 bandpass filters

30, 32 matching circuit

34 unbalanced to balanced converter

36 antennas

40, 42 Transmitter

44, 46, 48 receiving end

50 low temperature co-fired ceramic substrate

52, 56 conductive layer

54, 58 metal vias

60 inks

62 surface electrodes

Detailed ways

FIG. 1 is a block diagram showing a front-end module 10 of a quad-band mobile communication system according to an embodiment of the present invention. As shown in Figure 1, the front-end module 10 includes a frequency duplexer (Diplexer) 12, two transceiver switches (Transmit/ReceiveSwitch) 14 and 16, two low-pass filters (Low-pass Filter) 18, 28, four bands Band-pass filters (Band-pass Filter) 20, 22, 24 and 26, two impedance matching circuits (Impedance Matching Circuit) 30, 32 and an unbalanced to balanced converter (Balun Transformer) 34.

In addition, the antenna 36 can feed the received signal into the front-end module 10 and enter the receiving end 44 , 46 or 48 of the mobile communication system, or send signals from the system transmitting end 40 , 42 through the front-end module 10 in parallel. The frequency duplexer 12 is composed of two sets of frequency filter circuits (filters). The frequency resonance of the filter circuits can transmit signals of different frequency ranges separately. The transceiver switches 14 and 16 are respectively configured corresponding to different frequency ranges of the frequency duplexer circuit 12 to selectively switch the antenna 36 to the transmitting end or the receiving end of the communication system to transmit or receive signals.

For example, when the front-end module 10 of the present invention receives a radio frequency signal through the antenna 36 , the radio frequency signal first enters the frequency duplexer 12 . The present embodiment is exemplified as a front-end module architecture applicable to a four-band mobile communication system, so the PCS 1900 and DCS 1800 system frequency bands belonging to the high-frequency range can enter the transceiver switch 14 along the upper path of Fig. 1, and the GSM900 and the GSM900 belonging to the low-frequency range The GSM850 system frequency band enters another transceiver switch 16 along the lower path in the figure. The transceiver switches 14 and 16 can be switched to different positions to form different signal transmission or reception paths. When the transceiver switch 14 is switched to the receiving position, the PCS 1900 and DCS 1800 frequency band signals in the high frequency range can be passed by the bandpass filters 20 and 22 After being separated, they enter the receiving end 44 and the receiving end 46 respectively. Here, when the received signal is connected to the two filters 20 and 22 of different frequencies at the rear end through the transceiver switch 14, the two filters 20 and 22 cannot be directly matched, so the frequency band of the PCS 1900 and DCS 1800 systems An impedance matching circuit (Impedance Matching Circuit) 30 needs to be provided between the pass filters 20 and 22, so as to avoid signal strength reduction or interference with adjacent channels due to signal reflection.

Furthermore, when the transceiver switch 16 is switched to the receiving position, the GSM900 and GSM850 frequency band signals in the low frequency range can be separated by another set of bandpass filters 24 and 26 . In order to match the chip design of the mobile communication system, an impedance matching circuit 32 needs to be set between the receiving end 48 of the GSM850 and GSM900 system frequency bands and the bandpass filters 24 and 26, and an unbalanced to balanced converter (Balun Transformer) needs to be set. ) 34 is connected between the impedance matching circuit 32 and the receiving end 48, so as to convert the two unbalanced outputs (Unbalance signal) of the bandpass filters 24 and 26 of the GSM850 and GSM900 system frequency bands into a single signal with the minimum loss. The balance signal (Balance signal) output by the terminal.

Conversely, when the transceiver switch 14 is switched to the transmitting position, the DCS 1800/PCS 1900 frequency band signal of the high frequency range sent by the transmitter 40 can be filtered by the low-pass filter 18 and fed into the antenna 36; when the transceiver switch 16 When switching to the transmitting position, the low-frequency GSM850/GSM900 frequency band signal sent by the transmitting end 42 can be filtered by the low-pass filter 28 and fed into the antenna 36 .

According to this embodiment, the bandpass filter can be a surface acoustic wave filter (SAW Filter), which utilizes the high Q characteristic of the piezoelectric material to process the input signal of the electric wave to achieve a good effect of filtering unnecessary signals and noise . It should be noted that the transceiving switch is composed of at least one RLC circuit and diode components, and the low-pass filter, band-pass filter, unbalanced-to-balanced converter and frequency duplexer are all composed of LC circuits.

Please refer to FIG. 2 , the front-end module 10 for the mobile communication system of the present invention is composed of a multi-layer Low Temperature Cofired Ceramic (LTCC) substrate 50 . The low temperature co-fired ceramic substrate 50 is mainly composed of a ceramic dielectric material and contains many conductive layers therein.

In detail, the front-end module 10 of the present invention is patterned to form a low-temperature common The inside of the ceramic substrate 50 is fired. Since these components are composed of passive components such as resistors, capacitors, and inductors, passive components such as resistors, capacitors, and inductors are formed inside the low-temperature co-fired ceramic substrate 50 of each layer, and the front end of the present invention can be implemented. The modules are integrated into each layer of low temperature co-fired ceramic substrate 50 . Except for passive components, semiconductor components are placed on the surface of the substrate 50 by surface mount (SMT).

As shown in FIG. 3A , during the fabrication process, the inductors are patterned in strips on the conductive layers 52 inside the low temperature co-fired ceramic substrate 50 of each layer to form strip electrodes, and there is a dielectric between the conductive layers 52 . layer (not shown), and the conductive layer 52 is connected by a metal via hole (viahole) 54 , therefore, the connection pattern of the inductor in the multilayer low temperature co-fired ceramic substrate 50 is a spiral pattern. As shown in FIG. 3B again, capacitors are formed on the conductive layers 56 inside the low-temperature co-fired ceramic substrate 50 of each layer in a block patterned manner to form block electrodes, and there is a dielectric layer (not shown) between each conductive layer 56. , and the conductive layers 56 are connected by a metal via hole (via hole) 58, therefore, the connection type of the capacitor inside the multilayer low temperature co-fired ceramic substrate 50 is an overlapping type. The transceiver switch is a diode component placed on the surface of the substrate 50 in a surface mount manner, and can be electrically connected to the LC circuit formed by the capacitor and the inductor through the metal via hole.

Please refer to FIG. 2 again. The resistors are fabricated by printing ink 60 with resistive properties between the surface electrodes 62 of the low-temperature co-fired ceramic substrate 50 on the surface according to a specific aspect ratio. As far as the surface layer of the low temperature co-fired ceramic substrate 50 is concerned, in addition to resistors, other semiconductor components such as ICs and diodes are also included on the surface. The LC circuits in the low-temperature co-fired ceramic substrate 50 of each layer below the low-temperature co-fired ceramic substrate 50 on the surface layer are also connected to the low-temperature co-fired ceramic substrate 50 on the surface layer through the metal vias 54 and 58 between the above-mentioned conductive layers. The resistors on the board are electrically connected to semiconductor components such as ICs and diodes.

Since the ceramic substrate has a high dielectric value, the semiconductor components and passive components can be effectively integrated and the volume of the components can be greatly reduced after the components are patterned and embedded in the multilayer ceramic substrate for integration. Therefore, the front-end module 10 of the present invention can meet the requirements of module miniaturization and low cost at the same time.

Furthermore, the present invention can be matched to the architecture of the front-end module of the quad-band mobile communication system, and certainly includes the designs applied to the tri-band or dual-band mobile communication system. For example, if it is applied to a three-band mobile communication system, it is only necessary to omit the design of the band-pass filter 24 that passes the GSM850 frequency band signal.

The foregoing are examples only, not limitations. Any equivalent modifications or changes made without departing from the spirit and scope of the present invention shall be included in the claims.

Claims (10)

1. front-end module that is used for mobile communication system comprises:

One frequency diplexer is connected to an antenna;

At least one transceiver toggle switch is connected to this frequency diplexer circuit, switches transmitting terminal or the receiving terminal of this antenna to this mobile communication system with selectivity;

At least two band-pass filter is connected between this transceiver toggle switch and this receiving terminal;

At least one low pass filter is connected between this transceiver toggle switch and this transmitting terminal;

At least one impedance matching circuit is connected between two these band pass filters; And

One is non-equilibrium to balanced to unbalanced transformer, is connected between this impedance matching circuit and the receiving terminal.

2. the front-end module that is used for mobile communication system as claimed in claim 1, wherein this frequency diplexer comprises the individual circuits of handling one first band limits and one second band limits, and this transceiver toggle switch is to different frequency range range circuit configuration that should frequency diplexer.

3. the front-end module that is used for mobile communication system as claimed in claim 2, wherein this first band limits comprises PCS1900 and DCS1800 system frequency range, and this second band limits comprises GSM900 and GSM850 system frequency range.

4. the front-end module that is used for mobile communication system as claimed in claim 1, wherein this band pass filter is a surface acoustic wave filter.

5. the front-end module that is used for mobile communication system as claimed in claim 1, wherein this frequency diplexer, this band pass filter, this low pass filter, this impedance matching circuit, this non-equilibriumly is made of capacitor, inductor and resistor to balanced to unbalanced transformer and this transceiver toggle switch circuit of part, and this capacitor, inductor and resistor form on the multilayer low-temperature co-fired ceramic substrate in the patterning mode.

6. the front-end module that is used for mobile communication system as claimed in claim 5 wherein has a plurality of conductive layers and a plurality of dielectric layer in such low-temperature co-fired ceramic substrate, and is provided with the metallic conduction through hole between this conductive layer.

7. the front-end module that is used for mobile communication system as claimed in claim 5, the wherein pattern of this capacitor pattern shape in the shape of a spiral that is block and this inductor.

8. the front-end module that is used for mobile communication system as claimed in claim 5, wherein this resistor is the ink film with resistance.

9. the front-end module that is used for mobile communication system as claimed in claim 5 wherein has semiconductor subassembly on the top layer of this low-temperature co-fired ceramic substrate, and this semiconductor subassembly is attached on this top layer in the surface mount mode.

10. the front-end module that is used for mobile communication system as claimed in claim 9, wherein this semiconductor subassembly comprises the diode assembly of this transceiver toggle switch, and this diode assembly is electrically connected with this conductive layer via this metallic conduction through hole.

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